/* net_select.c */
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <netinet/in.h>
#define PORT 4321
#define MAX_QUE_CONN_NM 5
#define MAX_SOCK_FD FD_SETSIZE
#define BUFFER_SIZE 1024
int main()
{
struct sockaddr_in server_sockaddr, client_sockaddr;
int sin_size, count;
fd_set inset, tmp_inset;
int sockfd, client_fd, fd;
char buf[BUFFER_SIZE];
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
perror("socket");
exit(1);
}
server_sockaddr.sin_family = AF_INET;
server_sockaddr.sin_port = htons(PORT);
server_sockaddr.sin_addr.s_addr = INADDR_ANY;
bzero(&(server_sockaddr.sin_zero), 8);
int i = 1;/* 允许重复使用本地地址与套接字进行绑定 */
setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &i, sizeof(i));
if (bind(sockfd, (struct sockaddr *)&server_sockaddr,
sizeof(struct sockaddr)) == -1)
{
perror("bind");
exit(1);
}
if(listen(sockfd, MAX_QUE_CONN_NM) == -1)
{
perror("listen");
exit(1);
}
printf("listening....\n");
/*将调用socket()函数的描述符作为文件描述符*/
FD_ZERO(&inset);
FD_SET(sockfd, &inset);
while(1)
{
tmp_inset = inset;
sin_size=sizeof(struct sockaddr_in);
memset(buf, 0, sizeof(buf));
/*调用select()函数*/
if (!(select(MAX_SOCK_FD, &tmp_inset, NULL, NULL, NULL) > 0))
{
perror("select");
}
for (fd = 0; fd < MAX_SOCK_FD; fd++)
{
if (FD_ISSET(fd, &tmp_inset) > 0)
{
if (fd == sockfd)
{ /* 服务端接收客户端的连接请求 */
if ((client_fd = accept(sockfd,(struct sockaddr *)&client_sockaddr, &sin_size))== -1)
{
perror("accept");
exit(1);
}
FD_SET(client_fd, &inset);
printf("New connection from %d(socket)\n", client_fd);
}
else /* 处理从客户端发来的消息 */
{
if ((count = recv(client_fd, buf, BUFFER_SIZE, 0)) > 0)
{
printf("Received a message from %d: %s\n",client_fd, buf);
}
else
{
close(fd);
FD_CLR(fd, &inset);
printf("Client %d(socket) has left\n", fd);
}
}
} /* end of if FD_ISSET*/
} /* end of for fd*/
} /* end if while while*/
close(sockfd);
exit(0);
}

